Two of Silicon Valley's biggest venture capitalists are madly investing in tech startups that could soon make health care better and more affordable.

Health care is the "most screwed up" industry in the nation, said John Doerr, a longstanding partner at Kleiner Perkins Caufield & Byer known for backing companies like Google, Amazon, Intuit and Zynga.

The U.S. spends $2.6 trillion on health care and "everyone agrees that about 30% of that is wasted," he said at the TechCrunch Disrupt conference on Wednesday in San Francisco.

He thinks the problem is that doctors are charging per procedure, which encourages more procedures and general inefficiency. Doctors can change that by using iPads and cloud apps, he believes.

"Two or three years ago there was more technology in Safeway than in some physicians offices," he quipped.

Low-cost consumer health care apps on smartphones will be what really makes health care better, said another legendary VC, Vinod Khosla, founder of Khosla Ventures, at the same conference.

"80% of what doctors do can be done at a fraction of cost at substantial better quality," by using smartphones and low-cost sensors Khosla said.

He showed off a number of smartphone apps that he's invested in that could replace expensive diagnostic procedures.

AliveCor: An iPhone app that monitors your heart electrocardiogram (EKG). He's trying to convince the founders to give it away for free, he said.

CellScope Oto: Takes a photograph of the ear and ear temperature to diagnose ear infections and other illnesses.

GINGER.io: Monitors how you use your smartphone to track your mental health. Watches emails, phone calls, app usage. If you're normal behavior changes, it can alert you or your psychiatrist.